1. Field of the Invention
This invention relates to a chuck assembly, more particularly to a chuck assembly with a sealing member for preventing hydraulic fluid from entering into a clearance between a shaft and a sleeve of the chuck assembly.
2. Description of the Related Art
U.S. Pat. No. 6,497,417 discloses a conventional chuck assembly 1 that includes a housing 10 defining an inner space, a shaft 11 mounted co-axially and rotatably in the inner space and defining a chuck-receiving space 13 which has an enlarged end portion defining a piston-receiving chamber 131, a sleeve 12 secured to the housing 10 and sleeved on the shaft 11 so as to define a clearance 14 therebetween, a bearing unit 18 disposed between the sleeve 12 and the shaft 11, a chuck unit mounted in the chuck-receiving space 13 and including a plurality of jaws 16 for holding a workpiece (not shown), and a piston 15 mounted in the piston-receiving chamber 131, displaceable in an axial direction, and connected to the jaws 16 in such a manner that axial displacement of the piston 15 results in radial displacement of the jaws 16. The piston 15 subdivides the piston-receiving chamber 131 into first and second compartments 1311, 1312. A fluid channel 17 is formed in the chuck assembly 1, is in fluid communication with the first compartment 1311 of the piston-receiving chamber 131, and is adapted to be connected to a hydraulic fluid supply (not shown) so as to permit flow of pressurized hydraulic fluid into the first compartment 1311, thereby resulting in axial displacement of the piston 15.
Due to a large amount of the pressurized hydraulic fluid penetrating through the clearance 14, which can result in contamination of the chuck unit and the workpiece and a significant loss of the hydraulic fluid, a plurality of fluid passages 19 are required to be formed in the sleeve 12 and the housing 10, and a plurality of hydraulic fluid collectors (not shown) are required for collecting the hydraulic fluid. As a consequence, the dimensions of the chuck assembly 1 are increased considerably.
The disclosure of U.S. Pat. No. 6,497,417 is incorporated herein by reference.